Radio buttons on Rails

As in this previous post, with a slight twist:

<div class="form_row">
    <label for="theme">Theme:</label>
    <% [ 'plain', 'desert', 'green', 'corporate', 'funky' ].each do |theme| %>
      <br><%= radio_button_tag 'theme', theme, @theme == theme %>
      <%= theme.humanize %>
    <% end %>
</div>

Where

@theme = params[:theme]